In recent years, the importance of lithium ion batteries, nickel hydride batteries and other secondary batteries as vehicle-mounted batteries and power sources for personal computers and mobile phones has increased. In particular, much is expected of lithium secondary batteries, which are lightweight and achieve high energy density, as batteries able to be advantageously used as vehicle-mounted high output power sources. In a typical constitution of this type of secondary battery, an electrode has a constitution whereby the material capable of reversibly storing and releasing lithium ions (an electrode active material) is held by an electrically conductive member (an electrode current collector). For example, a typical example of an electrode current collector used in the positive electrode (a positive electrode current collector) is a sheet-shaped or member comprising mainly aluminum or an aluminum alloy. In addition, a typical example of an electrode active material used in a positive electrode (a positive electrode active material) is an oxide that contains lithium and one or two or more transition metal elements as constituent metal elements (a lithium-transition metal composite oxide).
In cases where a lithium-transition metal composite oxide is used as a positive electrode active material, the lithium-transition metal composite oxide has low electron conductivity, and is therefore generally used in combination with an electrically conductive material. For example, in a typical constitution of this type of positive electrode, a lithium-transition metal composite oxide, which is a positive electrode active material, is blended with a carbon powder as an electrically conductive material, and a positive electrode is formed by binding this mixture on the surface of a positive electrode current collector by means of a binder. An electrically conductive path is formed between the positive electrode active material and the positive electrode current collector due to the presence of the carbon powder, thereby enabling the transfer of electrons between the positive electrode active material and the positive electrode current collector. Prior art relating to this type of electrode is disclosed in, for example, Patent Literature 1 to 3.